When Kristin was 12 years old, her primary care doctor took note of the fact that she was obese, and talked to her about healthy eating and exercise. Kristin tried several diets, which failed, and by the time she was 14, her weight shot up to more than 180 pounds. She began restricting herself to 1,500 calories daily and ran 7 miles every day. In three years, Kristin lost more than 80 pounds, but also experienced dizziness and stopped getting her period. Her mother worried she had developed an eating disorder, and on several occasions, brought her daughter to her primary care doctor, who assured her Kristin’s body mass index — a measure of weight relative to height — was “appropriate.” By the time Kristin had an eating disorder assessment, she had significant fear of weight gain, restrictive eating, binging, persistent back pain and had experienced multiple stress fractures.

Kristin’s is one of two cases described in a new Pediatrics paper, published Monday, that says overweight and obese children and teens who lose weight are at significant risk for developing eating disorders, but their symptoms are often overlooked. It raises questions about the formal criteria used for diagnosing eating disorders, and suggests there may be a significant blind-spot among the doctors who treat children and teens. “These case studies really represent a phenomenon we’re seeing in our clinic more and more,” study author Leslie Simm, an eating disorders expert with the Mayo Clinic Children’s Center, told HuffPost. “Thirty-five percent of kids who are coming in with anorexia nervosa — with restricted eating and significant weight loss — started out in the ‘obese’ or ‘overweight’ weight range. And it takes them about a year longer to be identified.”

Public health efforts have drawn national attention to the harms associated with childhood obesity, among them; overweight children are more likely to have high blood pressure and cholesterol; are at greater risk of Type 2 diabetes and asthma; and are more likely to be obese as adults. Recent Centers for Disease Control and Prevention estimates found that among preschool-age children, obesity rates are dropping, but in the United States, roughly one-third of children and teens are obese or overweight.